1. Field of the Invention
The present application relates to an arrangement and method for enhancing the cooling capacity of portable personal computers. More particularly, the invention is directed to the provision of an arrangement for increasing the cooling capacity of laptop computers which are constrained in size, weight and power consumption, through which transfers and dissipates heat from semiconductor chips located in the computer and which are to be cooled, to the rear side of a liquid-crystal display of the laptop computer.
The capacity and performance of portable personal computers, such as laptop computers, notebook computers or the like, has recently been enhanced to such an extent that; for example, since the beginning of 1996, the thermal dissipation requirements of portable personal computers (PCs) have increased from about 10 watts to presently about 50 watts and potentially even higher values. This increase in the thermal dissipation requirements is a result of ever increasing CPU performance and additional functionality; such as DVD, modem, audio and the like, which are provided by future PCs. As elucidated in an article by Albert Yu, AThe Future of Microprocessors@, IEEE Micro, December 1996, pages 46 through 53, the trend of increasing power dissipation in the form of heat for portable personal computers will continue in the foreseeable future. Thus, at the widely employed A4 form factor for a portable personal computer; for instance, the cooling limit for a portable PC without a cooling fan is currently in excess of 20 watts and possibly up to 50 watts. Thus, providing a greater cooling capacity than the current limits in order to meet the anticipated thermal dissipation requirements of future portable personal computers, represents not only a potential competitive advantage in industry, but also provides a significant product differentiation from currently available and commercially sold portable personal computers.
In essence, as set forth hereinabove, the power consumption of laptop computers, especially the power of the CPU is continually increasing in the computer technology. Thus, for instance, the total power of a laptop computer is usually above 10 watts and has now increased to the range of about 30 to 50 watts or higher, whereas CPU power has increased from about 3 to 6 watts and, conceivably, can be as high as in the 40 watts range. Most of this power will eventually be dissipated in the form of heat to the surroundings. Consequently, being able to disperse increased amounts of heat from the laptop computer becomes a critical factor in the design and commercial aspects of laptop computers. This may be accomplished through the incorporating into the computers of not only passive heat dissipating or heat sink structures such as fins, heat pipes, or the like, but also of active heat transfer devices, possibly in the form of fans and similar features.
2. Discussion of the Prior Art
Various arrangements and devices for increasing the cooling capacities of laptop or personal computers are currently known in the technology.
Janik et al. U.S. Pat. No. 6,212,069 B1 discloses a thermally efficient portable computer wherein electronics are mounted on the display side of the portable computer having two separate plates, one for electronics and one for the display. The two plates can be brought into contact when the portable computer is closed and wherein the heat spreader comprises a separate component from an insulating rear cover closer to a display module when the portable computer is not in use, and for moving the heat spreader and insulating rear cover a distance away from the display module during use of the portable computer. This enables the spreading of the heat and efficient cooling of the heat spreader, however, is not concerned with transferring and dissipating heat from a CPU located in the main box of the computer.
Haley et al. U.S. Pat. No. 6,181,555 B1 discloses a cooling system for integrated circuit chips arranged in a portable computer wherein a lid having integrated circuit components requiring heat dissipation is provided with a flexible expansion structure under the action of a spring providing for passageways in order to enable the flow of cooling air between a module and display assembly.
Goto et al. U.S. Pat. No. 6,069,791 discloses a cooling device for notebook personal computers, wherein a flow passageway for cooling medium is located rearwardly of a liquid crystal display in the cover portion of the personal computer. This construction facilitates the transfer of heat from the main box of the computer to a display side in which a heat sink is positioned within a cavity rearwardly of the liquid crystal display, and wherein air is permitted flow within the cavity around the heat sink to effectuate heat dissipation.
Haley et al. U.S. Pat. No. 5,982,617 discloses an arrangement for cooling the electronics which are arranged in a separate structure rearwardly above a liquid crystal display panel, and wherein flow of air is adapted to pass intermediate initially spaced components.
Although the foregoing personal computer or laptop computer constructions each provide various types of methods to enable the heat transfer and dissipation thereof from electronic components, such as from computer chips or CPUs arranged within a personal computer, the present invention is directed to an improved arrangement and method of dissipating heat for essentially conventional portable computers in which most of the heat generating components, such as the CPU (central processing unit) are located in the main box, and wherein heat is transferred to a display component such as a cover hingedly connected to the main box and mounting the liquid crystal display. Moreover, the inventive arrangements for causing the heat to be transferred from the CPU and dissipated are unlike the prior art and provide for an expedient and highly efficient method of dissipating the generated heat.
Pursuant to a first embodiment of the invention, a thermal hinge interconnecting the main box housing the CPU and the cover housing the display is employed to conduct a portion of the heat generated by the central processing unit (CPU) to heat spreaders located rearwardly of the liquid crystal display, and wherein generally flexible bellows-shaped air duct is connected between the outlet of a cooling fan located proximate the CPU to the inlet of a channel defined by two spaced heat spreaders rearwardly of the display. Air is forced into the channel from the bottom of the cover towards top edge of the cover housing the display, in that the fan is adapted to draw heated air away from the electronics or CPU into the air duct and into the channel formed by the heat spreaders so as to be conducted to the surroundings.
Pursuant to a modified embodiment of the invention, the heated air generated by the electronics or CPU in the main box structure of the computer is conducted rearwardly by the action of the fan and diverted into a free space externally of the main box and rearwardly of the display cover mounting the liquid crystal display, wherein self-retractable air diverter means is employed to maintain the airflow close to the outer surface of the display cover.
Accordingly, it is an object of the present invention to provide a portable device, such as a portable personal computer or the like, wherein improved cooling of the electronics contained in a main box is effected by an air stream emanating from a fan located proximate the CPU to cause the air to flow through a thermal hinge into a channel between heat spreaders rearwardly of a liquid crystal display housed in a cover portion which is hingedly connected to the main box.
Pursuant to another object of the invention, the air flow is directed from the fan through a flexible bellows type thermal hinge interconnecting the cover portion mounting the liquid crystal display, and the main box housing the heat-generating electronic components, is directed therefrom into a heat spreading channel extending between heat spreaders rearwardly of the liquid crystal display and the cover of the portable computer so as to be conducted to the surroundings.
In accordance with another object of the invention, the flow of air emanating from the main box containing the electronic components or CPU is directed into a free space rearwardly of the cover housing the liquid crystal display, and a mechanism adapted to open and close an air diverter automatically responsive to opening and closing of the display cover is provided to enable the heated airflow to discharge into the surrounding rearwardly of the computer cover.